A can package is used for a package structure that is sealed in an airtight manner and has high environment resistance, a package structure of a sensor or the like, which includes a window portion, or a package structure requiring an electrostatic shield. For example, Patent Document 1 discloses a pyroelectric infrared sensor with a can package structure.
In the pyroelectric infrared sensor disclosed in Patent Document 1, an alumina substrate on which a predetermined rectangular electrode pattern is formed, a field effect transistor (FET), and a supporting base are arranged on a stem, a window portion is formed on a can case, and an optical filter is bonded to the window portion. The can case is firmly fixed to the stem so as to be sealed.
Patent Document 1: Japanese Unexamined Patent Application Publication No. 8-128895
A can package including a stem and a can case is configured by fitting an cavity of the can case with a supporting base portion of the stem and performing resistance welding. A fitting tolerance is defined between the outer diameter of the supporting base portion of the stem and the inner diameter of the cavity of the can case. This generates a predetermined gap between the outer diameter of the supporting base portion of the stem and the inner diameter of the cavity of the can case in a state where the can case is made to cover the stem. That is to say, the gap is previously provided so as to make “fitting” at the time of assembly even when the outer diameter of the disk-like supporting base portion of the stem and the inner diameter of the cavity of the can case have fluctuations in dimensions.
However, relative rotation slippage is easy to be generated between the can case and the stem at the time of the resistance welding. This requires an operation for restricting the rotation slippage between the can case and the stem immediately before the resistance welding. Further, the can case and the stem are combined with no tightening force during storage in a state where the can case and the stem are combined before the resistance welding. Due to this, they are easy to be slipped or detached and work efficiency is not preferable.